1. Field of the Invention
The present invention relates to an electrically-operated two-wheeled vehicle provided with a first rotary electric machine and a second rotary electric machine.
2. Description of Background Art
Recently, there has been developed an electrically-operated two-wheeled vehicle provided with a swing unit which pivotally supports a rear wheel constituting a drive wheel in a state where the swing unit is mounted on a vehicle body. A rotary electric machine which is a drive source of the electrically-operated two-wheeled vehicle is mounted on this kind of swing unit.
In making use of a rotary electric machine as a drive source, an output of the rotary electric machine is determined based on a required drive force. When a required value is large, a method which increases a size of one rotary electric machine and a method which combines a plurality of rotary electric machines are considered. As a vehicle which adopts a latter method, for example, there has been proposed a hybrid vehicle which includes a so-called multi-layered coaxial rotary electric machine where a first rotary electric machine and a second rotary electric machine are arranged coaxially (see JP-A-2004-147410, for example).
This multi-layered coaxial rotary electric machine is configured such that the second rotary electric machine is arranged radially outside the first rotary electric machine so as to surround the first rotary electric machine. Due to such a constitution, a width size of the first rotary electric machine in the axial direction can be shortened.
In an electrically-operated two-wheeled vehicle, to achieve a wide operation region, it may be possible to arrange a plurality of rotary electric machines described above, for example. However, when the plurality of rotary electric machines are simply arranged parallel to each other along the vehicle widthwise direction, there arises a drawback that a thickness of a swing unit becomes large and hence, the center of weight of a vehicle is offset to the outside in the vehicle widthwise direction.
In view of the above-mentioned drawback, it may be possible to provide the above-mentioned multi-layered coaxial rotary electric machine in the swing unit. In this case, however, a diameter of the second rotary electric machine which is positioned outside the first rotary electric machine becomes large and hence, when a diameter of a rear wheel is small as in the case of a scooter-type electrically-operated two-wheeled vehicle, a height position of a lower surface of the swing unit becomes excessively low whereby there arises a drawback that a possibility that the swing unit is brought into contact with a ground surface (road surface) is increased.